ZHCS927G May 2012 – January 2018 CDCM6208
PRODUCTION DATA.
Before the device outputs turn on after power up, the device goes through the following initialization routine:
STEP | DURATION | COMMENTS |
---|---|---|
Step 1: Power up ramp | Depends on customer supply ramp time | The POR monitor holds the device in power-down or reset until the VDD supply voltage reaches 1.06 V (min) to 1.26 V (max) |
Step 2: XO startup (if crystal is used) | Depends on XTAL. Could be several ms;
For NX3225GA 25 MHz typical XTAL startup time measures 200 µs. |
This step assumes RESETN = 1 and PDN = 1.The XTAL startup time is the time it takes for the XTAL to oscillate with sufficient amplitude. The CDCM6208 has a built-in amplitude detection circuit, and holds the device in reset until the XTAL stage has sufficient swing. |
Step 3: Ref Clock Counter | 64k Reference clock cycles at PFD input | This counter of 64 k clock cycles needs to expire before any further power-up step is done inside the device. This counter ensures that the input to the PFD from PRI or SEC input has stabilized in frequency. The duration of this step can range from 640 µs (fPFD= 100 MHz) to 8 sec (8 kHz PFD). |
Step 4: FBCLK counter | 64k FBCLK cycles with CW=32; The duration is similar to Step 3, or can be more accurately estimated as:
V1: approximately 64k x PS_A x N/2.48 GHz V2: approximately 64k x PS_A x N/3.05 GHz |
The Feedback counter delays the startup by another 64k PFD clock cycles. This is so that all counters are well initialized and also ensure additional timing margin for the reference clock to settle. This step can range from 640 µs (fPFD= 100 MHz) to 8 sec (fPFD= 8kHz). |
Step 5: VCO calibration | 128k PFD reference clock cycles | This step calibrates the VCO to the exact frequency range, and takes exactly 128k PFD clock cycles. The duration can therefore range from 1280 µs (fPFD= 100 MHz) to 16 sec (f PFD= 8 KHz). |
Step 6: PLL lock time | approximately 3 x LBW | The Outputs turn on immediately after calibration. A small frequency error remains for the duration of approximately 3 x LBW (so in synthesizer mode typically 10 µs). The initial output frequency will be lower than the target output frequency, as the loop filter starts out initially discharged. |
Step 7: PLL Lock indicator high | approximately 2305 PFD clock cycles | The PLL lock indicator if selected on output STATUS0 or STATUS1 will go high after approximately 2048 to 2560 PFD clock cycles to indicate PLL is now locked. |